This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Bacterial toxins cause various pathological effects. The current study proposes to investigate the structure and function of selected CDC Category-A bacterial toxins. The primary aim is to understand the mechanism by which toxins recognize and attack their host, and to develop drugs to treat or prevent toxin related illness. Due to the safety concern, we are working with genetically modified forms of toxins that are inactivated and nontoxic.